1. Field of the Invention
The present invention relates to apparatus for automatically treating pieces of exposed photosensitive paper particularly for automatic cameras of a type for obtaining standard size pictures for cards, identity cards and the like.
2. Description of Prior Art
Automatic cameras of the above mentioned type are known, in which a sheet or coupon of photosensitive paper, e.g. obtained by cutting a paper roll, is exposed in a conventional manner in a chamber and is then conveyed to a treatment system designed to successively dip the coupon into developing, fixing and possibly reversal, as well as washing baths, in an automatic way, thereby providing to the user a finished photograph delivered through an outlet slot.
The treatment system may have various configurations. In one of such systems, a chain having paper-retaining members such as teeth and the like successively conveys the coupon from one tank to another and in this case the path of the chain has loops which extend inside the tanks. According to another system, the coupon is conveyed to a basket carried by an arm designed to successively immerse the basket in suitable treatment tanks until completion of the developing, reversal and/or fixing and washing treatment has occurred.
In both such known treatment systems the dwelling or stay time of the coupon to be developed in the various successive baths are determined in a quite rigid way, in view of the requirement that more than one coupon should be treated in succession without waiting for termination of the treatment of the preceding coupon, and in practice such times are limited to values which are in integer-number ratios. In fact, e.g. with the chain system, immersion durations in each bath, bearing in mind that the chain must move uniformly and can carry different coupons to different sectors, are determined by the length of the immersed loops in each bath. It is then possible, while designing the machine, to establish the number of loops the chain has to follow in each bath, thereby obtaining times equal to 1, 2, 3, . . . times a basic time. Similarly, in the basket arm system one may obtain times 1, 2, 3 times a base time by arranging a plurality of adjacent tanks containing the same bath in a number proportional to the required dwelling time. Rigidity in determining the times results in the necessity for a machine user to use baths prepared in predetermined dilutions.
The above mentioned treatment systems also have the serious inconvenience of continuously transporting small amounts of liquid out of a bath by way of the conveying member of the coupon which is the chain in the first case, and the basket in the second case. The amount of liquid carried away from one bath and placed in the successive bath is relatively great, e.g. at least of the order of the amount absorbed by the coupon. Consequently, the above mentioned conveying systems cause considerable pollution in each bath owing to the liquid coming from a preceding bath, which results in premature deterioration of the baths. This then results in higher cost for removal of the baths and higher maintenance costs due to higher frequency at which the machine has to be attended for replacement or restoration of the baths. Such additional maintenance costs are particularly undesirable when, as often happens with this kind of automatic camera, the machines are located in positions far from each other on an urban area although they are administered by a single administrator.